Ceramic Circuit Board Brazing for Thick Cu Layers on Oxide Substrates
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Solution Overview
Problem
Existing ceramic circuit boards face high manufacturing costs due to the use of silver-based brazing materials and multiple paste layers, and they struggle to form thick circuit layers with sufficient bonding strength to ceramic substrates, especially when using oxide substrates like alumina.
Innovation Solution
A ceramic circuit board design using a Cu-Mg based brazing material containing additional elements like Sn, Sb, Bi, and active metal elements such as Ti, Zr, Hf, V, Nb, Ta, Cr, and W, which forms a metal circuit layer with enhanced bonding strength and flexibility through an interfacial reaction layer, eliminating the need for pre-formed Mo layers and reducing reliance on silver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silver-based brazing materials are used, then bonding strength is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive silver-based brazing materials with copper-based brazing materials containing Mg and active metal elements. This substitution maintains adequate bonding strength while significantly reducing manufacturing cost, as copper is much cheaper than silver.
Solution Approach 2:
The patent changes the chemical composition parameters of the brazing material from silver-based to copper-based systems with specific additions of Mg (1-25 at%) and active metal elements (0.1-10 at%). This compositional parameter change enables cost reduction while achieving the required bonding strength through the synergistic effect of these elements.
2Strength
If multiple paste layers are laminated, then bonding strength is improved, but process cost increases
Solution Approach 1:
The patent merges the functions of multiple paste layers into a single brazing material composition. Instead of applying separate layers for adhesion and conductivity, the invention uses one integrated copper-based brazing material containing Mg and active metal elements that simultaneously provides bonding strength, adhesion to ceramic substrate, and electrical conductivity.
Solution Approach 2:
The copper-based brazing material with Mg and active metal elements serves multiple functions simultaneously: it acts as the bonding agent between metal and ceramic, provides the conductive metal layer, and ensures adequate adhesion without requiring separate Mo layers or multiple paste applications. This multi-functionality simplifies the manufacturing process.
3Reliability
If thick circuit layers are formed, then heat dissipation and conductivity are improved, but bonding strength with ceramic substrate decreases
Solution Approach 1:
The patent changes the compositional parameters of the brazing material to include Mg (1-25 at%) and active metal elements (0.1-10 at%) in the copper-based system. These parameter changes enable the formation of thick circuit layers (5-150 μm) while maintaining strong bonding to the ceramic substrate, as the active metal elements enhance interfacial adhesion even in thick deposits.
Solution Approach 2:
The patent uses a composite brazing material system combining Cu, Mg, and active metal elements (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, or W). This composite material structure allows thick circuit layers to be formed with both excellent bonding strength and heat dissipation performance, as the composite composition provides superior interfacial bonding compared to conventional single-phase materials.
4Strength
If Mo layer is formed on oxide substrate, then adhesion is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates the need for separate Mo layers from the manufacturing process. Instead of applying a Mo layer before the copper-based brazing material, the invention uses the Cu-Mg-active metal element system that directly bonds to the oxide substrate, thereby removing an unnecessary step and reducing manufacturing cost while maintaining adhesion.
Solution Approach 2:
The copper-based brazing material with Mg and active metal elements performs the adhesion function that would otherwise require a separate Mo layer. The active metal elements in the brazing material itself provide the interfacial bonding capability, making the Mo layer redundant and allowing a single-material system to achieve both bonding and adhesion functions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a ceramic circuit board with increased bonding strength and design flexibility in circuit layer thickness, reducing costs and improving heat dissipation and conductivity while minimizing void formation and warpage.
Implementation Method 1
the bonding strength between a circuit layer and a ceramic substrate with suppressing cost... forms a metal circuit layer with enhanced bonding strength and flexibility through an interfacial reaction layer
Implementation Method 2
heating and holding the ceramic substrate on which the brazing material for circuit formation has been placed
Data Source
AI summary
A low-cost ceramic circuit board that offers enhanced design flexibility in circuit layer thickness by increasing the bonding strength between a circuit layer and a ceramic substrate. A ceramic circuit board includes a ceramic substrate and a metal circuit layer formed on the ceramic substrate. The metal circuit layer contains Cu, Mg, at least one element selected from the group including Sn, Sb, and Bi, and at least one active metal element selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W.